/* https://leetcode.com/problems/remove-duplicates-from-sorted-array
 * (Easy)  26. Remove Duplicates from Sorted Array
 * Given a sorted array nums, remove the duplicates in-place such that each
 * element appear only once and return the new length.
 * Do not allocate extra space for another array, you must do this by modifying
 * the input array in-place with O(1) extra memory.
 *
 * Example 1:
 * Given nums = [1,1,2],
 * Your function should return length = 2, with the first two elements of nums
 * being 1 and 2 respectively.
 * It doesn't matter what you leave beyond the returned length.
 *
 * Example 2:
 * Given nums = [0,0,1,1,1,2,2,3,3,4],
 * Your function should return length = 5, with the first five elements of nums
 * being modified to 0, 1, 2, 3, and 4 respectively.
 * It doesn't matter what values are set beyond the returned length.
 *
 * Clarification:
 * Confused why the returned value is an integer but your answer is an array?
 * Note that the input array is passed in by reference, which means
 * modification to the input array will be known to the caller as well.
 * Internally you can think of this:
 * ```
 * // nums is passed in by reference. (i.e., without making a copy)
 * int len = removeDuplicates(nums);
 *
 * // any modification to nums in your function would be known by the caller.
 * // using the length returned by your function, it prints the first len
 * //   elements.
 * for (int i = 0; i < len; i++) {
 *     print(nums[i]);
 * }
 * ```
 */


/* runtime: 16ms, memory: 7.9MB */
int removeDuplicates(int *nums, int numsSize) {
  if (!numsSize) return 0;
  int *left = nums, *right = nums;
  while (--numsSize) if (*left - *++right) *++left = *right;
  return left - nums + 1;
}


/* Test removeDuplicates */
#include <assert.h>
#define LEN(array) (sizeof(array) / sizeof*(array))
#define REMOVE_DUPLICATES(...) \
  { \
    int nums[] = {__VA_ARGS__};
#define SHOULD_BE(...) \
    int expected[] = {__VA_ARGS__}; \
    int len = removeDuplicates(nums, LEN(nums)); \
    assert(LEN(expected) == len); \
    for (int i = 0; i < len; ++i) assert(expected[i] == nums[i]); \
  }
int main() {
  REMOVE_DUPLICATES() SHOULD_BE()
  REMOVE_DUPLICATES(0) SHOULD_BE(0)
  REMOVE_DUPLICATES(0, 0) SHOULD_BE(0)
  REMOVE_DUPLICATES(0, 1) SHOULD_BE(0, 1)
  REMOVE_DUPLICATES(1, 1, 1) SHOULD_BE(1)
  REMOVE_DUPLICATES(1, 1, 2) SHOULD_BE(1, 2)
  REMOVE_DUPLICATES(1, 2, 2) SHOULD_BE(1, 2)
  REMOVE_DUPLICATES(0, 1, 2) SHOULD_BE(0, 1, 2)
  REMOVE_DUPLICATES(0, 0, 1, 1, 1, 2, 2, 3, 3, 4) SHOULD_BE(0, 1, 2, 3, 4)
}
